It is well known to utilize fuel filter assemblies to filter fuel for a combustible engine of a motor vehicle. Such fuel filter assemblies typically comprise a sideways or downwardly mounted canister having a paper filter media enclosed in the canister. The fuel enters and fills the canister so that all of the filter media is doused with fuel as the fuel passes through the paper filter media and exits the canister to travel to the engine. Various contaminants are filtered from the fuel that would degrade the performance of the engine if left within the fuel. After a certain amount of filtration, the contaminants begin to obstruct the filter media and restrict fuel flow through the filter media. Since the entire filter media is doused in fuel, fuel flow restriction steadily increases during the useful life of the filter media. Restricted fuel flow degrades the performance of the engine, and if unattended, could lead to continued degradation of performance as well as mechanical and structural failure of the engine's components.
As fuel flows through the filter media, a pressure differential occurs across the filter media as the unfiltered side of the filter media realizes a higher pressure from the fuel than does the filtered side. When the filter media is unobstructed, the pressure differential is at a minimum since fuel is relatively free to flow through the unobstructed filter media. When the filter media becomes obstructed, the pressure differential increases as pressure increases on the unfiltered side of the filter media to force the fuel through the obstructed filter media. This can lead to contaminants being forced through the filter media, essentially, tearing the filter media. Typically, when the useful life of the filter media has expired, the filter media is replaced, although no method or apparatus is provided that accurately determines when the filter media should be replaced. It is well known to provide transparent canisters to view the condition of the filter media, but there is still no indication as to how obstructed the filter media is or to what extent fuel flow is being restricted.
With the advent of electronically controlled fuel injection engine systems, fuel filter systems are playing an ever increasingly important role in reducing and eliminating contaminants in fuel. Such fuel injection systems utilize extremely high injection pressures and, therefore, are extremely sensitive to restrictive fuel flows and various contaminants.
There are many known contaminants which will effect the performance of a fuel injection system. Due to the high injection pressures of fuel injection systems, minute quantities of water damage injectors by destroying internal lubrication and by causing galling and erosion of spray holes and tips. Also, such fuel injector systems now expose fuel to repeated heating and cooling cycles as fuel flows through cylinder heads and around fuel injectors of engines. This creates water condensation in fuel tanks as well as microbial growths and polymerization of fuel components. All of these contaminants contribute to a shortened fuel filter life as the contaminants begin to obstruct the filter media and restrict fuel flow.
As mentioned earlier, the problem of an obstructed fuel filter is typically remedied by replacing the filter media, but since the contamination formation rate in the fuel varies with temperatures, crude stocks and time, it is not easy to determine the status of serviceability or the remaining useful life of a conventional fuel filter. As the demand on fuel filter systems to filter such a wide range of contaminants increases, the price of such fuel filters increase, and therefore, it is not desirable to prematurely replace a fuel filter. A high rate of fuel filter replacement creates problems with fuel filter disposal, disposition cost of used filters, and environmental considerations. Also, when servicing fuel filter assemblies, concern must be given to fuel that is still within the fuel filter assembly after venting the assembly so that such fuel does not escape into the environment or be allowed to exit into the fuel outlet without having been filtered and treated.
As previously described, the heating and cooling cycles of fuel involved in fuel injector systems may promote the growth of microorganisms such as bacteria and fungi. Such microorganisms create problems of sludge, clogged fuel filters and corrosive by-products that damage storage tanks, fuel lines, filters, injection pumps, injectors, burners, governors and other control mechanisms. Microorganisms deplete special additives for gasoline, gasohols and alternative fuels needed for octane and cetane improvement as well as depleting other chemicals that improve performance or comply with environmental and clean air requirements.
It is well known to douse fuel tanks or bulk storage tank reservoirs with fuel additives when microorganic infections are found. Generally, once the microorganisms are found, a great amount of damage and contamination has occurred resulting in expensive maintenance, replacement of components and filters as well as the stoppage of furnaces and engines. Several attempts have been made to provide a fuel filter that not only filters fuel but also provides a fuel additive for destroying microorganisms in the fuel. Such fuel additives are typically released manually and have no means by which to slowly release the fuel additive or release the fuel additive when microorganisms have reached an unacceptable level. Also, none of these attempts provide a method or means by which to replace the fuel additive or accurately gage the need to replace the fuel additive.
It would be desirable to provide a fuel filter assembly that provided a constant level of restricted fuel flow through the fuel filter assembly during the useful life of the filter media by utilizing a minimum amount of filter media to obtain the least possible restricted fuel flow while also providing a fuel additive whose addition is proportionally related to the amount of filter media required to provide the lowest possible level of restricted fuel flow. It would also be desirable to provide a fuel filter system that provided an accurate and simple means by which to gage the useful life of the filter media and the fuel additive. In addition, it would be desirable to provide a multi-purpose access means for easily removing and/or replacing the fuel additive, for venting the fuel filter assembly, and for priming the fuel filter assembly without disassembling the fuel filter assembly. It would also be desirable to provide a means for collecting excess fuel upon venting and draining the fuel from the fuel filter so that fuel does not escape the fuel filter housing or exit unfiltered and untreated into the fuel outlet. Lastly, it would also be desirable to provide a fuel filter media and fuel additive that could be discarded without having cost and environmental concerns.